The long-term objective of this proposal is to pioneer the application of near-field optical microscopy in a variety of biological arenas. The near-field optical microscope is a lensless optical microscope with resolution approximately ten times higher than that of a conventional optical microscope. It is designed for use in aqueous environments. The instrument was recently developed by engineers and physicists, but, to our knowledge, has not yet been applied to answer biological or clinical questions. The proposal contains three specific aims: (1) to apply our prototype microscope in a number of diverse biological settings, with particular emphasis on testing each of several possible imaging modalities; (2) on the basis of the experience gained in (1), to build a more robust, versatile, 'user friendly' unit that is relatively more accessible to individual researchers; and (3) to use the instruments in (1) and (2) to answer biologically relevant questions. The applications span the range from basic science, to clinical science, to biotechnology. The include: chromosomal mapping, cytoskeletal enzyme localization, ciliary motility, embryonic development metabolism, hydrogel porosity, and nano-scale bioengineering of materials. By the end of the grant period we expect to have a second or third generation near-field optical microscope that has undergone thorough testing by biologists, who can then integrate the microscope into their future research.